Materials Science · Cross-listed from cond-mat.soft
Folding-Driven Auxetic Weft Knit Textiles with Integrated Capacitive Sensing
Kausalya Mahadevan, Helen E. Read, Anya X. Zhang et al. (+3 more)
Machine knitting provides a scalable platform for manufacturing multifunctional textiles in which geometry, mechanics, and embedded functionality can be programmed at the stitch level. However, predictive design tools capable of linking knit architecture to large-deformation mechanical response remain limited. Here, we develop a reduced-order spring-network model that captures the relaxation, unfolding, and deformation of knitted fabrics composed of checkerboard arrangements of rib and garter patches. The model accurately predicts the corrugated relaxed configuration of the knits and the
evolution of local deformations under tensile loading using only linear extensional and torsional springs. Combining simulations with experiments, we show that the programmed unfolding of the corrugations generates tunable auxetic behavior, with both the magnitude of the negative Poisson's ratio and the strain at which it occurs governed by the unit-
cell geometry. We further integrate capacitive strain sensing directly during fabrication through partial plating of conductive yarns, eliminating post-processing. The resulting knitted capacitors exhibit programmable tradeoffs between strain sensitivity and sensing range, enabling either highly sensitive sensors over narrow deformation windows or lower-sensitivity sensors capable of measuring larger strains. Together, our modeling framework and fabrication strategy provide a route toward the rational design of mechanically programmable, sensorized knits with tailored shape-morphing and sensing functionalities.
Read the full abstract ▾
All authors Kausalya Mahadevan, Helen E. Read, Anya X. Zhang, Louis-Justin Tallot, Michelle C. Yuen, Katia Bertoldi
Materials Science
Twist-configured moire-moire reconstruction governs diverse commensurate double-moire phases in twisted bilayer graphene on h-BN
Yuta Seo, Naoto Nakatsuji, Jimpei Kawase et al. (+6 more)
The coexistence of multiple moire
lattices in van der Waals
heterostructures raises a fundamental question: how do distinct moire patterns interact and reconstruct? Here, we investigate twisted
bilayer graphene (tBG) on hexagonal boron nitride (h-BN), where tBG and
graphene/h-BN moire structures coexist, using conductive atomic force microscopy combined with continuum-model simulations. We show that reconstruction between these moire
lattices-moire-moire reconstruction-manifests across multiple length scales, giving rise to diverse commensurate double-moire phases. Locally, the stacking registry between the two moire
lattices is uniquely selected by the global twist configuration (helical or alternate), mediated by rotational relaxation of the shared
graphene layer. This registry, together with twist angle and strain, governs commensurate domains from C3z-symmetric to strained
symmetry-modified structures. These results establish moire-moire reconstruction as a general framework for engineering structural and electronic order – including theoretically predicted topological flat bands below the magic angle – in multilayer moire materials.
Read the full abstract ▾
All authors Yuta Seo, Naoto Nakatsuji, Jimpei Kawase, Naoto Hishida, Kenji Watanabe, Takashi Taniguchi, Takuto Kawakami, Mikito Koshino, Tomoki Machida
Materials Science
First principles study of chalcogen vacancy effect on the optoelectronic and photocatalytic properties of transition metal dichalcogenides monolayers
Tahir Wahab, Antonio Cammarata and Tomas Polcar
In working conditions, chalcogen vacancies spontaneously occur in two-dimensional transition metal dichalcogenides (TMDCs) monolayers, affecting their optoelectronic and photocatalytic properties. To study how chalcogen vacancies affect such properties, we use
quantum mechanical calculations considering prototypical MX$_2$ (M = Mo, W, X = S and Se) TMDCs monolayers. Structural optimisations show that M-X bond lengths about a vacancy are different compared to the bond lengths in the pristine structure. Band structure calculations reveal that the introduction of vacancies produce electronic states about the
Fermi level, hence resulting in the reduction of the band gap. Work function and electrostatic potential calculations show that the introduction of vacancies induce an asymmetry in the electrostatic potential facilitating the charge separation; such feature is absent in a pristine monolayer. All the considered defective structures are capable of performing hydrogen
evolution reaction, while co-catalyst is required to perform oxygen
evolution reaction when used for water splitting. WS$_2$ and WSe$_2$ defective monolayers can serve as an efficient photocatalytic material for reducing CO$_2$ into useful chemical products. The presented results show that vacancy-containing TMDCs monolayers own photocatalytic capabilities compared to the pristine counterparts, thus showing that defective TMD monolayers have prospective applications and should not be regarded as flawed products to be discarded. Finally, the results might constitute guidelines for the experimental synthesis of vacancy-engineered MX$_2$ monolayers for optoelectronic devices and photocatalytic applications.
Read the full abstract ▾
Materials Science
Magnetic ordering in VI3: a van der Waals material combining vastly different magnetic anisotropies
K. K. Pokhrel, S. Ray, N. Machavcova et al. (+2 more)
Among
magnetic van der Waals materials, the vanadium trihalide family exhibits unique features. In particular, VI3 contains V atoms of two different types, as two energetically close electronic occupations can coexist in real samples. These types show strikingly different
magnetic anisotropy, predicted to differ by more than an order of magnitude. The combination forms a distinctive
magnetic system. VI3 also displays an unusual thickness dependence: the monolayer Curie temperature (TC) is higher than that of the bulk, contrary to the expectation that interlayer coupling reinforces
magnetic order. Using atomistic
spin-dynamics simulations informed by first-principles calculations, we investigate the critical temperature behavior from the combined perspective of single-ion anisotropy and exchange interactions. The strong anisotropy contrast significantly affects thermal stability: increasing the fraction of high-anisotropy sites raises the energy cost of transverse
spin fluctuations and increases the ordering temperature. Furthermore, V-atom inhomogeneity makes the interlayer super-superexchange network spatially nonuniform, creating competing exchange pathways. This weakens coherent interlayer order while preserving robust intralayer
ferromagnetic correlations, thus modifying the bulk-monolayer TC relation. Our model reproduces experimental TC values when the ratio of the two V types is close to 1:1, in agreement with two experimental methods. This supports the coexistence of two V configurations in VI3. The monolayer TC is reproduced with a slightly modified ratio, possibly linked to polaron concentration. The sensitivity of TC to this ratio suggests that the ordering temperature of VI3 can in principle be tuned over a broad range by controlling the relative occupation of the two vanadium configurations.
Read the full abstract ▾
All authors K. K. Pokhrel, S. Ray, N. Machavcova, A. Koliogiorgos, K. Carva
Materials Science
High-Entropy Nitride Photocatalysts for Visible-Light Antibiotic Degradation: Structural Stability, In Situ Interfacial Visualization, and Molecular-Level Mechanistic Insights
Zahoor Manzoor, Shamik Chowdhury, Raphael Benjamim de Oliveira et al. (+5 more)
High-
entropy nitrides (HENs) have emerged as a promising class of advanced materials with tunable electronic structures, high stability, and abundant active sites. The incorporation of nitrogen enhances visible-light absorption, promotes efficient charge separation, and improves structural robustness, making these materials highly suitable for photocatalytic applications. In this study, (MnFeCoNiCu)N-based HEN nanoparticles (NPs) were synthesized as visible-light-assisted photocatalysts for the degradation of antibiotics, including sulfamethoxazole (SME) and tetracycline (TCL). The catalyst exhibited excellent performance, achieving 96% degradation of SME and 94% removal of TCL within 2 h of visible-light irradiation. The photocatalytic activity was systematically evaluated under varying operational parameters, including solution pH, catalyst dosage, pollutant concentration, and the presence of coexisting ions. Notably, the catalyst maintained high efficiency in real water
matrices, demonstrating its practical applicability. The
entropy-stabilized nitride framework exhibited negligible metal leaching, excellent thermal and structural stability as confirmed by temperature-dependent synchrotron angle-dispersive X-ray diffraction, and stable performance over multiple reuse cycles. Furthermore, in situ
liquid-
cell transmission electron microscopy provided real-time insight into catalyst-pollutant interactions, while complementary molecular simulations revealed the structural stability of the HEN NPs during molecular adsorption and the distinct interaction modes of the two antibiotics. Phytotoxicity tests using Vigna radiata confirmed the effective detoxification of treated solutions. Overall, this work establishes (MnFeCoNiCu)N HENs as efficient and durable visible-light-driven photocatalysts for the removal of antibiotics from complex aqueous environments.
Read the full abstract ▾
All authors Zahoor Manzoor, Shamik Chowdhury, Raphael Benjamim de Oliveira, Marcelo Lopes Pereira Junior, Guilherme da Silva Lopes Fabris, Prikshat Dadhwal, Douglas S. Galvao, Chandra Sekhar Tiwary
Materials Science · Cross-listed from cond-mat.mes-hall
Intrinsic orbital Hall effect in a nonuniform electric field
Min Ju Park, Jongjun M. Lee and Hyun-Woo Lee
Geometric analysis of electronic Bloch states offers a universal framework for understanding electronic properties, yet its role in the transport of orbital angular momentum remains unexplored. In this work, we establish an analytic connection between orbital angular momentum transport and the
geometric properties of Bloch wave functions in electronic systems. Focusing on the intrinsic orbital
Hall effect in the dc limit under a spatially nonuniform electric field, we show that its conductivity can be expressed in terms of universal
geometric quantities, such as the orbital Berry
curvature and
quantum metric. This formulation provides a term-by-term correspondence with the
geometric description of intrinsic charge
Hall transport established in previous studies. Using a tight-binding model, we further illustrate that the higher-order orbital
Hall response can exhibit enhanced sensitivity to the orientation of an anisotropic sample. Our work deepens the understanding of diverse intrinsic transverse transport phenomena and the role of
quantum geometry in electronic systems.
Read the full abstract ▾
Materials Science
Bottlenecks in Hamiltonian-Adaptive Resolution Simulation Method for Modeling Interfaces
Hari Haran Sudhakar, Alessandra Serva and Rocio Semino
The
Hamiltonian-Adaptive Resolution Simulation (H-AdResS) method allows to combine atomistic and particle-based coarse-grained models in a single simulation box, which makes it very attractive to model systems containing interfaces or reactive regions surrounded by an interacting environment. In our previous work [J. Chem. Inf. Model. (2026) 66 (15): 9215-9225], we implemented H-AdResS in LAMMPS (2 Aug 2023 version) and extended its use to interfaces, focusing on MOF/CO$_2$ interfaces as an example. We found that, despite its advantages, using this method properly for this kind of systems is not trivial. In this work, an in-depth analysis of the impact of the choice of thermostatting schemes and long-range electrostatics models is presented. Even though its
Hamiltonian formulation enables performing H-AdResS simulations within constant temperatures ensembles, not every thermostat is appropriate. We demonstrate that Langevin thermostat is a reliable choice for this method, while Nosé-Hoover results in artifacts. In addition, we show that using short-range models such as the Damped Shifted Force method for electrostatics, a popular choice for H-AdResS simulations, can lead to non-physical results when modeling interfaces. The need of capping strategies to deal with discontinuities in forces and energies arising from abrupt changes in resolution is also discussed. Finally, the impossibility of changing the definition of the H-AdResS
Hamiltonian to include a gradual interpolation of the bonded degrees of freedom is discussed. We hope that this contribution helps the reader to appropriately set up H-AdResS simulations and to assess if this method can be used to accurately model their system of interest.
Read the full abstract ▾
Materials Science · Cross-listed from cs.AI
Grounded autonomous research: a fault-tolerant LLM pipeline from corpus to manuscript in frontier computational physics
Haonan Huang
Autonomous-research
agents have demonstrated end-to-end LLM automation in machine-learning sandboxes where execution provides calibration. Frontier physical science differs categorically: physical
reasoning underlies every methodology choice, toolchains are often underdocumented, and calibration must come from external literature anchors - which unscaffolded
agents cite but do not confront, hallucinating plausible, unverifiable results from internal priors. We present a pipeline that runs end-to-end from a corpus of 11,083 recent condensed-matter physics arXiv papers to a publication-grade manuscript with three substantive physics findings (here on altermagnetic piezomagnetism): the
agent autonomously conceives a research direction by mapping the corpus, calibrates methodology by reproducing published references, conducts novel first-principles computations, and writes the manuscript - grounded in literature throughout, across 47 fresh-context sessions in six phases sharing only on-disk state, with 2,162 literature-consultation events. Fault tolerance emerges from redundancy: fresh-context isolation, distributed grounding, and
adversarial review catch what any single session misses; pre- and post-pilot stages are fully autonomous, and pilot requires bounded human intervention only at reproduction failures - operational knowledge curation, not scientific direction. Two paired failure modes - a pre-architecture baseline and a no-pilot ablation - isolate structurally enforced numerical confrontation at calibration checkpoints as the operative grounding mechanism. The primitives, characterized failure modes, and quantified intervention pattern lay a foundation for autonomous research in high-stakes scientific domains beyond computational physics.
Read the full abstract ▾
Materials Science · Cross-listed from physics.chem-ph
Molecular interpretability of the bulk electrochemical impedance of concentrated electrolytes
Connie J. Fairchild, Stephen J. Cox, Benjamin Rotenberg et al. (+1 more)
Electrochemical impedance spectroscopy (EIS) is a widely used technique to understand time-dependent response and relaxation under applied voltage. While these spectra contain a wealth of information, major gaps in our understanding can hinder our ability to interpret EIS spectra in terms of microscopic chemical mechanisms. We propose an alternative approach to common empirical fitting procedures for describing the contribution of the bulk electrolyte to the EIS spectrum. This new approach is rooted in determining the moments of the frequency-dependent conductivity, with molecular interpretability provided by a generalized Langevin equation description of an effective single particle dynamics; the `itinerant oscillator' (IO) model. In contrast to a Debye–Falkenhagen description, the IO model makes no assumptions regarding the concentration of the electrolyte, a fact we demonstrate by analysing molecular dynamics simulations of a room-temperature ionic
liquid. By analysing the
memory function from simulation within the framework provided by the IO model, we reveal the importance of capturing the separation of timescales within the
memory function for describing the temperature dependent $\beta$-relaxation process. We go on to show how our impedance model directly reports on this distribution of timescales while retaining the simplicity of commonly employed workflows.
Read the full abstract ▾
All authors Connie J. Fairchild, Stephen J. Cox, Benjamin Rotenberg, Thomas Sayer
Materials Science
From Bloch to Néel: Anisotropy-dependent Domain-Wall Character in FePd Thin Films
Annika Stellhorn, Alicia Backs, Ekaterina Klyushina et al. (+11 more)
We report an experimental investigation of the depth-dependent domain wall formation in L1$_0$-FePd thin films with high perpendicular
magnetic anisotropy. Using circular dichroism X-ray resonant
magnetic scattering (CD-XRMS) as a function of the incident X-ray angle, we explore the depth
evolution of
chiral spin textures in two samples with different strengths of magnetocrystalline anisotropy. Combined with CD-STXM, CD-ptychography, and macroscopic characterization of the structural order,
magnetic properties, and surface morphology, we relate these observations to differences in the long-range order of the L1$_0$ phase of FePd. One FePd thin film with very high magnetocrystalline anisotropy, characterized by $Q_{PMA}=1.8$, exhibits an unexpectedly large Néel contribution. Angular-dependent CD-XRMS directly reveals a smooth transition from a hybrid Bloch-Néel chirality within the upper FePd layer towards a purely Néel-type structure at the lower FePd interface. In the second FePd sample, despite a still relatively large $Q_{PMA}=1.45$, the domain walls were found to be purely Néel type. These results indicate a crucial role of the long-range structural order in determining the formation of the
magnetic structure.
Read the full abstract ▾
All authors Annika Stellhorn, Alicia Backs, Ekaterina Klyushina, Connie Bednarski-Meinke, Steffen Tober, Denis Vasiukov, Oskar Stepančić, Vítor Alexandre de Oliveira Lima, Lukas Aniansson, Paul Steadman, Manuel Valvidares, Jörg Schwenke, Claudiu Bulbucan, Elizabeth Blackburn
Materials Science
Interfacial Strain and Structural Defects Govern the Performance of Tantalum Superconducting Waveguide Resonators
Moritz Singer, Harsh Gupta, Benedikt Schoof et al. (+3 more)
Tantalum (Ta) is a promising material for reaching long coherence times in superconducting
qubits. A detailed understanding of the underlying structure-property relationship remains elusive though. In the present study, we sputter-deposited 200 nm thick Ta films on high-resistivity silicon (100) substrates at temperatures ranging from T = 20{\deg}C to 600{\deg}C, as well as on different seed layers (Nb, TiN and TaN). Alpha-Ta thin films were readily obtained at temperatures above 500{\deg}C and on all seed layers. The films were characterized in terms of surface morphology, residual-resistance ratio,
crystal phase composition and superconducting transition temperature, as well as RF-performance using coplanar waveguide resonators. Internal quality factors of up to 1.5 million were measured at 100 mK in the single-
photon regime. Despite similar bulk material properties, alpha-Ta films on different seed layers exhibit markedly different RF-performance, which we attribute to dissimilar strain and structural defects at the substrate-metal interfaces. Williamson-
Hall analysis of XRD data reveals a clear correlation between decreasing microstrain and increasing quality factor. Cross-sectional HR-TEM further supports this interpretation by directly resolving interfacial disorder. Our results highlight the critical role of interface engineering in optimizing superconducting thin films for low-loss
quantum computing circuitry.
Read the full abstract ▾
All authors Moritz Singer, Harsh Gupta, Benedikt Schoof, Elena Willinger, Anton Orekhov, Marc Tornow
Materials Science
Efficient Large-Scale STEM-EELS Simulations With Torched-TACAW
Martin Osmera, João Vaz, Paul M. Zeiger et al. (+1 more)
The time auto-correlation of auxiliary wave functions (TACAW) method enables efficient simulations of ultra-low-loss electron energy loss spectra (EELS) arising from vibrational and
magnon excitations. In practical applications to realistic materials systems, however, TACAW calculations become challenging due to the large system sizes required for models containing defects, interfaces,
impurities, or grain boundaries, as well as the substantial computational cost and data throughput associated with molecular dynamics and multislice calculations. Here we discuss a practical methodology for large-scale TACAW simulations and present torched-TACAW, a freely available implementation of the TACAW part of the described workflow for efficient STEM-EELS simulations. The overall approach combines molecular dynamics based on foundational machine-learned interatomic potentials, partitioning of elongated supercells, and on-the-fly processing of multislice outputs in order to enable near ab initio quality simulations with tractable
memory use and data flow. Using rutile TiO2 as a model system, we analyze important numerical aspects of the method, including windowing and supercell partitioning, and demonstrate atomic-resolution STEM-EELS simulations for thick samples.
Read the full abstract ▾
All authors Martin Osmera, João Vaz, Paul M. Zeiger, Ján Rusz
Materials Science
Ultrafast Demagnetization Governed by Spin Fluctuations in CaRuO$_{3}$/SrTiO$_{3}$ Superlattice
Yu-Han Gao, Wen-Xiao Shi, Yuan-Sha Chen et al. (+10 more)
For ultrafast magnetization switching devices, critical slowing down in conventional ferromagnets near their Curie temperature constitutes a key challenge that must be overcome. In contrast to this typical behavior, we observe an anomalous acceleration of demagnetization in CaRuO$_{3}$/SrTiO$_{3}$ superlattices, a moderately correlated weak itinerant ferromagnet. The demagnetization rate increases with rising temperature, pump fluence, and applied
magnetic field. To explain these anomalous phenomena, we develop a phenomenological model integrating the three-temperature model with self-consistent renormalization theory. Because the intrinsic gradient magnetism of the superlattice suppresses the typical divergence of specific heat, the conventional thermodynamic bottleneck is bypassed. Our model reveals that this decoupling enables the ultrafast dynamics to be predominantly governed by the
spin-fluctuation-driven enhancement of the electron-
spin scattering vertex. Our work demonstrates how spatial inhomogeneity can decouple macroscopic thermodynamic singularities from microscopic scattering processes, offering a new paradigm for manipulating ultrafast
spin dynamics in correlated
quantum materials. The pronounced sensitivity of the demagnetization rate to external parameters further suggests the potential for designing highly tunable ultrafast spintronic devices that leverage enhanced fluctuations near the
magnetic instability.
Read the full abstract ▾
All authors Yu-Han Gao, Wen-Xiao Shi, Yuan-Sha Chen, Ji-Rong Sun, Qing-Lin Yang, Xu Yang, Zhuo Deng, Peng-Tao Yang, Zheng Chang, Hong-Mei Feng, Wei He, Xiang-Qun Zhang, Zhao-Hua Cheng
Materials Science
Differentiable inverse design of short-range order in high-entropy alloys: from target sro to target property
Tiancheng Ding and Conrard Giresse Tetsassi Feugmo
Short-range order (SRO) governs the mechanical response of multi-principal-element
alloys, but designing an
alloy for a target property usually means solving two disconnected problems: building a structure matching a desired SRO pattern, then separately checking its property, with no shared optimization. This work replaces the standard random-swap search (reverse Monte Carlo) with a gradient-based approach: atom occupancy is treated as continuous rather than fixed, so the whole process can be tuned using gradient descent, the same method used to train neural networks. This builder matches random-swap accuracy on small systems, but is six times faster and eight times more accurate on large 4000-atom systems, and scales smoothly to
alloys with many elements without extra bookkeeping. A physics-based correction term, adapted from prior two-element work and extended here to many elements, keeps designed structures thermodynamically realistic rather than just numerically matching the target SRO pattern. A small neural network then predicts mechanical properties directly from composition and SRO statistics, closing the loop from target property back to structure. Tested on nine face-centered-cubic and body-centered-cubic
alloys, the pipeline captured SRO-driven stiffness changes from -20% to +57%, and
cell-size checks showed at least 864 atoms are needed to get the direction and size of these changes right, since the commonly used 108-atom
cells can mislead. Against real simulations for a cobalt-chromium-nickel
alloy, the method matched three of four target stiffness values within 6%. The method is released as an open-source Python package, anisro, offering a practical route to gradient-based, property-driven
alloy design.
Read the full abstract ▾
Materials Science
Coherent two-dimensional electronic spectroscopy integrated with confocal back focal plane microscopy
Trideep Kawde, Pavel Trofimov, Anton Trenczek et al. (+3 more)
We introduce a setup for coherent two-dimensional electronic spectroscopy in the pump-probe reflection geometry that is integrated with a confocal back focal plane imaging microscope. The angle-resolved capability is utilized to control pump and probe wavevectors, while real space imaging enables co-localization of the collection spots for linear and ultrafast experiments. Compression of pulses down to 20 fs is achieved. We demonstrate the capabilities of this approach on an exfoliated WSe$_2$ monolayer on Si/SiO$_2$. The setup is suited to investigate
excitons and
exciton-polaritons in 2D Materials and their
heterostructures.
Read the full abstract ▾
All authors Trideep Kawde, Pavel Trofimov, Anton Trenczek, Matteo Russo, Jasper Wilhelm Schwering, Hélène Seiler
Materials Science · Cross-listed from cond-mat.mes-hall
Electrical transport in ultra-thin films: from Fuchs-Sondheimer to quantum-confinement
Alessio Zaccone
Ultra-thin films are fundamental components of modern nanoelectronics, where reducing thickness to the few-nanometer scale leads to a dramatic increase in electrical resistivity. For decades, this behavior has been interpreted in terms of classical size effects, primarily surface scattering within the Fuchs–Sondheimer theory and grain-boundary scattering in the Mayadas–Shatzkes model. While these approaches successfully describe transport when the film thickness is comparable to the electronic mean free path, growing experimental evidence indicates that they become insufficient under extreme confinement. This review discusses the crossover from classical scattering to a
quantum-confinement regime in which the electronic states available for transport are fundamentally restructured by finite size. We review the recently proposed reciprocal-space confinement theory, which predicts an exponential increase of resistivity with decreasing thickness at the nanoscale, and discuss how it can be combined with classical surface-scattering models to provide a unified description of ultra-thin metallic and semiconducting films. Finally, we summarize recent experimental evidence supporting this picture and discuss its implications for future nanoelectronic devices, nanoscale interconnects, and
quantum transport under extreme spatial confinement.
Read the full abstract ▾
Materials Science · Cross-listed from cond-mat.str-el
Unconventional Mixed-Parity Magnetism in Rare-Earth Tetraborides
Dong-Choon Ryu, Jae-Ho Han, Bongjae Kim et al. (+1 more)
Altermagnetism has advanced the study of compensated magnets by revealing non-relativistic
spin splitting, traditionally classified into strictly even- or odd-parity
spin textures. Here, we unveil a fundamentally different regime: component-resolved mixed-parity
spin splitting in a fully three-dimensional compensated magnet. Using first-principles calculations, tight-binding and $\mathbf{k} \cdot \mathbf{p}$ models, along with
spin-group
symmetry analysis, we demonstrate that the non-coplanar ground state of $\mathrm{TbB}_4$ enforces a unique momentum-space
spin texture. The in-plane
spin components exhibit odd-parity $p$- and $f$-wave-like textures, whereas the out-of-plane component retains an even-parity $d$-wave altermagnetic character. Crucially, the coexistence of the in-plane odd-parity textures is driven not by relativistic
spin-orbit coupling, but by a staggered Berry phase arising from the inherent scalar
spin chirality. This mixed-parity structure dictates distinct transport fingerprints, including bulk non-relativistic Edelstein and
spin Hall responses, as well as a
symmetry-allowed Berry
curvature dipole. These results establish the rare-earth tetraborides as a robust platform for engineering complex
spin-charge conversion phenomena.
Read the full abstract ▾
All authors Dong-Choon Ryu, Jae-Ho Han, Bongjae Kim, Chang-Jong Kang
Materials Science · Cross-listed from cond-mat.str-el
Plaid-Like Spin Splitting and Chirality of Magnon Bands in Antiferromagnetic MnTe$_2$
Dirk Wulferding, Daehyeon An, Jiwon Choi et al. (+8 more)
Altermagnets constitute an emerging class of
magnetic materials that combine compensated
antiferromagnetic order with
spin-split excitations arising from crystalline
symmetries. Despite strong theoretical interest, their experimental identification remains challenging. Here, we demonstrate that helicity- and angle-resolved Raman scattering measurements reveal reduced rotational
symmetries of
magnons and a pronounced imbalance between left- and right-circular polarization channels, indicating momentum-dependent
magnon handedness. First-principles DFT+$U$ calculations combined with linear
spin-wave theory uncover a characteristic plaid-like
spin-splitting structure in momentum space. The resulting
magnon spin textures are dictated by the unconventional sublattice
symmetries of MnTe$_2$ and closely emulate those of altermagnetic electronic bands. Our work provides evidence of
chiral spin-wave excitations unique to this non-coplanar antiferromagnet.
Read the full abstract ▾
All authors Dirk Wulferding, Daehyeon An, Jiwon Choi, Dongmin Mun, Youngsu Choi, Sivasakthi Kuppusamy, Sritharan Krishnamoorthi, Raman Sankar, Myung Joon Han, Se Kwon Kim, Kwang-Yong Choi
Materials Science
Anisotropic nanoscale coherent polariton transport in CrSBr
Paritosh Malik, Dogyun Ko, Vita Solovyeva et al. (+11 more)
In a combined experimental and theoretical study, we demonstrate anisotropic polariton transport on the nanoscale in the van der Waals antiferromagnet CrSBr. While effective cavity-polariton formation emerges via the self-hybridization of ultra-high oscillator strength
excitons with a thin slab photonic mode, the absence of external mirrors facilitates spectroscopic investigation of these polaritons via cathodoluminescence (CL) on length scales determined by the electron wavelength. This direct access allows us to perform precise charting of the polariton landscape with nanometric resolution, and to probe polariton interference phenomena. The main finding of the work highlights that the coherent polariton transport follows the $C_{2v}$
symmetry of CrSBr, allowing exclusive transport along the crystallographic a-axis, while no coherent feature is found along the b-axis direction. Our work sets the foundation to use CL spectroscopy in cavity-polaritonics in more advanced landscapes, such as photonic
crystals or optical
lattices, and establishes the technique as a powerful tool to probe anisotropic expansion and relaxation phenomena on the nanoscale
Read the full abstract ▾
All authors Paritosh Malik, Dogyun Ko, Vita Solovyeva, Chirag Chandrakant Palekar, Imad Limame, Sven Rodt, Kseniia Mosina, Zdeněk Sofer, Alexander Steinhoff, Martin Esmann, Stephan Reitzenstein, Bo Han, Christopher Gies, Christian Schneider
Materials Science
A depth resolved investigation of hydrogen uptake in carbon based nanostructures by soft-to-hard photoemission spectroscopy
Orlando Castellano, Alice Apponi, Luca Cecchini et al. (+11 more)
Hydrogen chemisorption on graphitic carbon modifies the carbon orbital hybridization from sp2 to sp3, altering both structural and electronic properties. Understanding not only the lateral extent but also the depth distribution of hydrogen uptake in three-dimensional carbon architectures is essential for both fundamental studies and storage applications. To this end, we investigate here the
evolution of the C 1s core-level lineshape in nanoporous
graphene (NPG) and vertically aligned carbon nanotubes (CNTs) upon hydrogenation, exploiting soft-to-hard X-ray photoemission spectroscopy to achieve a depth-resolved analysis. Decomposition of the C 1s spectra reveals the formation of an sp3 rich overlayer, indicating hydrogen chemisorption limited to the outermost accessible surfaces in both systems. These results clarify the depth distribution of hydrogen in curved and porous graphitic networks and provide quantitative constraints on its chemisorption for carbon-based hydrogen storage applications.
Read the full abstract ▾
All authors Orlando Castellano, Alice Apponi, Luca Cecchini, Daniele Paoloni, Simone Ritarossi, Francesco Pandolfi, Ilaria Rago, Tien-Lin Lee, Samuel Jeong, Yoshikazu Ito, Carlo Mariani, Gianluca Cavoto, Francesco Offi, Alessandro Ruocco
Materials Science
Transition-Metal Tailored $Ga_{2}O_{2}$ Monolayer: From Room-Temperature Gas Sensing to Chemical Scavenging
Afreen Anamul Haque and Aniket Singha
Pristine $Ga_{2}O_{2}$ monolayers suffer from poor sensitivity and weak molecular capture, limiting their application in toxic gas detection and environmental detoxification. Here, we employ first-principles density functional theory (DFT) calculations to investigate the gas sensing and scavenging properties of $Ga_{2}O_{2}$ monolayers substitutionally tailored via seven transition-metals (TM): Pd, Zn, Zr, Mo, Ag, Ti, and Pt. All TM-substituted monolayers exhibit negative formation and binding energies, negligible
lattice distortion, and structural stability in molecular dynamics simulations. Performance evaluation against eight toxic industrial and three environmental gases reveals functionalities ranging from selective, reusable room-temperature sensing to permanent molecular capture. Ag substitution exhibits exceptional selectivity for $NO$ with moderate adsorption strength (~-0.83eV), an up to eight-order-of-magnitude conductivity enhancement, besides facilitating reusable $O_2$ and $NO_2$ detection. Additionally, Pd-, Zn-, Zr-, and Mo substitutions tune selectivity toward $NO$, $NO_2$, $CO_2$, $CO$, and $O_2$. Coming to applications towards toxic gas capture, Zr- and Mo-substituted systems selectively scavenge oxidizing gases, whereas Ti and Pt act as universal scavengers. Further analysis reveals that Pd- and Ag-substituted monolayers remain selective for $NO$, while Zn substitution favors $NO_2$ detection even in ambient atmospheric conditions. Thus, these tailored $Ga_{2}O_{2}$ monolayers offer a practical platform for atmospheric monitoring and detoxification.
Read the full abstract ▾
Materials Science
HVAF Spraying of NiTi Coatings: Microstructure, Phase Transformation and Shape Memory Behavior
Sneha Samal, Shrikant Joshi, Stefan Björklund et al. (+8 more)
Depositing various coatings on surface of engineering components with the aim to improve their performance concerning wear, corrosion, friction and thermal protection is already a standard practice. Depositing metallic NiTi shape
memory alloy coatings may be a viable alternative for hard ceramic coatings. NiTi coatings offer additional benefits originating from unique functional thermomechanical properties. However, fabrication of thick NiTi coatings turned out to be difficult. Standard electroplating and
laser cladding methods are not suitable for NiTi the most widely used
plasma spray methods tend to produce chemically inhomogeneous coatings that do not transform martensitically, cold sprayed NiTi coatings suffer from poor adhesion to the substrates. In this work we report on first ever successful fabrication of thick NiTi coatings (100-300 um) that display functional thermomechanical properties and simultaneously show very good adherence to the substrate. We used high velocity air fuel thermal spray method to fabricate NiTi coatings deposited on mild steel using four different sets of processing parameters. Chemical composition, porosity, microstructure, phase transformation and functional thermomechanical properties of the NiTi coatings were evaluated. Although the coatings contain inhomogeneous microstructure, voids,
oxide particles, high density of dislocation defects and internal stress, they undergo martensitic transformation upon cooling and or mechanical loading. As sprayed NiTi coatings need to be annealed to display functional thermomechanical properties. Despite their limited tensile strength, the coatings displayed thermal actuation in 3 point bending tests and shape
memory effects in nanoindentation and scratch tests.
Read the full abstract ▾
All authors Sneha Samal, Shrikant Joshi, Stefan Björklund, Mohit Chandra, Akhil Bhardwaj, Jaromír Kopeček, Stanislav Habr, Lukáš Václavek, Jan Tomáštík, Ondřej Tyc, Petr Šittner
Materials Science
Quantifying angular momentum of coherently driven circular phonons
Roman Mankowsky, Serhane Zerdane, Shih-Wen Huang et al. (+9 more)
The use of intense terahertz (THz) pulses to manipulate low-energy excitations offers a powerful approach for ultrafast control of electronic and
magnetic properties in materials. Theory suggests that circular ionic motions driven by THz fields carry angular momentum, potentially generating internal
magnetic fields. Recent experiments in nonmagnetic SrTiO3 (STO) have hinted at such THz-induced fields, but their origin remains debated. Here, we employ ultrafast x-ray diffraction to resolve the time-dependent ionic trajectories in STO following excitation by circularly polarized THz pulses. Our analysis reveals that oxygen ions, despite their lower mass, contribute around 90% of the
phonon angular momentum. The resulting imbalance between the negatively and positively charged ions provides a clear explanation for the mechanism behind induced magnetism in STO. This work further provides the first quantitative measurement of circular ionic motions and their angular momentum and establishes a general methodology for the investigation of angular momentum transfer in solids, paving the way for new strategies to control topological
phonon transport and
phonon-driven magnetism in
quantum materials.
Read the full abstract ▾
All authors Roman Mankowsky, Serhane Zerdane, Shih-Wen Huang, Mathias Sander, Xin Liu, Danylo Babich, Martina Basini, Puneet Kaur, Jan-Chi Yang, Michael Fechner, Urs Staub, Henrik Lemke
Materials Science
Density functional study of native point defects in CaO
Yunhwa Jo and Minseok Choi
We investigate the structural, electronic, and optical properties of native point defects in CaO using first-principles density-functional calculations. Oxygen vacancies are favored under O-poor conditions, whereas calcium vacancies dominate under O-rich conditions. Calculated migration barriers and binding energies indicate that vacancy complexes are thermodynamically stable and can survive high-temperature annealing. Optical transition energies, evaluated using the Franck-Condon framework, suggest that several experimentally observed absorption and emission peaks can be attributed to negatively charged vacancy complexes as well as isolated oxygen vacancies.
Read the full abstract ▾